Liquid crystal display device and mobile telecommunication terminal using the same

ABSTRACT

A liquid crystal display device and a mobile telecommunication terminal using the same can display messages such as information on a calling party, a received message, and temporal information even when a folding cover is not open by using a double-faced liquid crystal display device. The double-faced liquid crystal display device includes a first substrate having a common electrode, a second substrate having n scan electrodes and m signal electrodes, a liquid crystal layer disposed between the first and second substrates, a polarizer, and a reflector, wherein the liquid crystal display device is divided into a first region and a second region, and the polarizer and the reflector are symmetrically disposed so that the first region is displayed in a first direction and the second region is displayed in a second direction.

REFERENCES TO RELATED APPLICATIONS

[0001] This application claims the benefit of Korean Patent ApplicationNo. 22782/1999, filed on Jun. 17, 1999, the entirety of which is herebyincorporated by reference for all purposes as if fully set forth herein

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a double-faced liquid crystaldisplay device and a mobile telecommunication terminal using the same.

[0004] 2. Description of the Related Art

[0005] A related art liquid crystal display device will be describedwith reference to the accompanying drawings.

[0006]FIG. 1 is a sectional view showing a related art liquid crystaldisplay device, and FIG. 2 is a schematic view showing a double-faceddisplay device based on the related art liquid crystal display device.

[0007] As shown in FIG. 1, the related art liquid crystal display deviceincludes a lower substrate 13, an upper substrate 12, and a liquidcrystal 14. The lower substrate 13 includes a scan electrode pattern, asignal electrode pattern, and a pixel electrode pattern. The uppersubstrate 12 includes a common electrode pattern, a black matrix, and acolor filter layer. The liquid crystal 14 is implanted between the uppersubstrate 12 and the lower substrate 13.

[0008] Polarizers 11 and 15 are respectively disposed on the uppersubstrate 12 and below the lower substrate 13 to compensate a phasedifference due to refraction of light when characters, numbers orfigures are displayed. A reflector 16 is disposed on the bottom of thepolarizer 15 to reflect light.

[0009] The upper substrate 12 and the lower substrate 13 between whichthe liquid crystal 14 is implanted are formed of glasses or films havingexcellent transmittivity of light. The electrode patterns formed in theupper substrate 12 and the lower substrate 13 may be of dot matrixtypes, segment types, or a mix of dot matrix and segment types.

[0010] In some applications, it is desirable to provide a double-faceddisplay; that is, a display that can be viewed from two faces, orsurfaces. One example of such an application is a folding cover typemobile telecommunicative terminal such as a cellular telephone. In thistype of application, it is desirable to have a double-faced display withone display viewable on the inside of the folding cover for displayinginformation when the phone is in use by a user, and a second displayviewable on the outside of the cover, which allows information such ascaller identification information to be displayed to a user withoutrequiring the user to open the phone.

[0011] The construction of a related art double-faced display device fordisplaying characters, numbers and/or figures on two faces using twoconventional liquid crystal display devices of the type discussed abovewill now be described.

[0012] As shown in FIG. 2, the related art double-faced display deviceincludes first and second liquid crystal display devices 26 a and 26 bhaving respectively, signal electrodes and scan electrodes, a controller21 for analyzing an input video signal and outputting a control signalfor displaying characters, numbers or figures, a first memory 22comprising a volatile memory device, for temporarily storing an inputsignal and storing booted data to promptly process the operation of thecontroller 21, a second memory 23 comprising a nonvolatile memorydevice, for storing an operational algorithm of the controller 21, afirst driver 24 a for driving the signal electrodes and the scanelectrodes of the first liquid crystal display device 26 a in accordancewith a control signal of the controller 21 to display a video signal, asecond driver 24 b for driving the signal electrodes and the scanelectrodes of the second liquid crystal display device 26 b inaccordance with the control signal of the controller 21 to display avideo signal, and first and second frame memories 25 a and 25 b forstoring signals for displaying characters, numbers or figures, appliedfrom the first and second drivers 24 a and 24 b.

[0013] In other words, in a conventional double-faced display, there areprovided two liquid crystal display devices having separate signalelectrodes and scan electrodes, and two drivers for, respectively, thetwo liquid crystal display devices.

[0014] The operation of the conventional double-faced display device, inwhich one liquid crystal display device is attached on a front face anda second liquid crystal display device is attached on a rear face, willnow be described.

[0015] When power is supplied to the system, the controller 21 accessesan operation program stored in the second memory 23 and detects thesignals for displaying externally input characters, numbers or figuresin a state that the system is initially booted.

[0016] At this time, if the externally input signals are detected, thecontroller 21 analyzes the input signals through the operationalalgorithm and analysis program set in the first and second memories 22and 23 and applies the control signal for displaying characters, numbersor figures to the first and second drivers 24 a and 24 b.

[0017] The first and second drivers 24 a and 24 b apply a driving signalfor displaying corresponding characters, numbers or figures to the scanelectrodes and the signal electrodes of the first and second liquidcrystal display devices 26 a and 26 b attached on inner and outersurfaces of the system for double-faced display, so that the samecharacters, number or figures can respectively be displayed on the firstand second liquid crystal display devices 26 a and 26 b.

[0018] At this time, the first and second frame memories 25 a and 25 bprocess and store the control signal applied from the controller 21 fora frame. Then, the first and second frame memories 25 a and 25 b outputthe frame signal stored in corresponding memory areas in accordance withaccess signals of the first and second drivers 24 a and 24 b, so thatcorresponding characters, numbers or figures can stably be displayed onthe first and second liquid crystal display devices 26 a and 26 b.

[0019] However, the related art double-faced display device has severaldrawbacks.

[0020] First, to display characters, numbers or figures on two faces,two liquid crystal display devices must separately be provided. To drivethe two liquid crystal display devices, two drivers corresponding to thetwo liquid crystal display devices must be provided. To simultaneouslydisplay two faces, a duplicated control algorithm is used. Thisincreases power consumption and thus increases the production cost.

[0021] Furthermore, since the two drivers are provided to drive the twoliquid crystal display devices, a large area is required in the system.This makes it difficult to produce a light-weight and slim-sizedproduct. For example, in a folding cover type mobile telecommunicationterminal, in order to display identification information for a callingparty without opening the folding cover, two liquid crystal displaydevices must be provided, one attached on an inner face of the cover andthe other on the outer face of the cover. This makes a light-weight andslim-sized folding cover type mobile telecommunication terminaldifficult. Also, since the expensive liquid crystal display devices anddrivers are additionally provided, the cost of the terminal increases.

SUMMARY OF THE INVENTION

[0022] Accordingly, the present invention is directed to a liquidcrystal display device and a mobile telecommunication terminal using thesame that substantially obviates one or more of the limitations anddisadvantages of the related art.

[0023] An object of the present invention is to provide a double facedliquid crystal display device and a mobile telecommunication terminalusing the same, in which one liquid crystal display device displaysinformation on two faces so that messages such as caller identificationinformation, a received message, and temporal (e.g., time and date)information can be displayed even when a folding cover is not open.

[0024] Another object of the present invention is to provide a liquidcrystal display device and a mobile telecommunication terminal using thesame, in which production costs can be saved and a slim-sized andlight-weight mobile telecommunication terminal can be achieved.

[0025] Additional features and advantages of the invention will be setforth in the description which follows, and in part will be apparentfrom the description, or may be learned by practice of the invention.The objectives and other advantages of the invention will be realizedand attained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

[0026] To achieve these and other advantages in accordance with thepresent invention, as embodied and broadly described herein, a liquidcrystal display device according to the present invention includes afirst substrate having a common electrode, a second substrate having nscan electrodes and m signal electrodes, a liquid crystal layer disposedbetween the first and second substrates, a polarizer, and a reflector,wherein the liquid crystal display device is divided into a first regionand a second region, and the polarizer and the reflector aresymmetrically disposed so that the first region is displayed in a firstdirection and the second region is displayed in a second direction.

[0027] In another aspect, a liquid crystal display device includes afirst substrate, a second substrate disposed below the first substrate,a liquid crystal layer disposed between the first substrate and thesecond substrate, a first front polarizer disposed above and extendingover a first portion of the first substrate, a first rear polarizerdisposed above and extending over a second portion of the firstsubstrate, a first reflector disposed above the rear polarizer andextending over the second portion of the first substrate, a second rearpolarizer disposed below and extending under a first portion of thesecond substrate, a second reflector disposed below the second rearpolarizer and extending under the first portion of the second substrate,and a second front polarizer disposed below and extending under a secondportion of the second substrate.

[0028] In other aspect, a mobile telecommunication terminal includes afolding cover movable between an open position and a closed position,having a window in a predetermined area, a liquid crystal display devicehaving a first region and a second region, the first and second regionsbeing displayed to oppose each other, and the liquid crystal displaydevice being mounted an inner side of the folder cover to externallydisplay the second region through the window, and a driver for drivingthe liquid crystal display device.

[0029] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are intended to provide further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this specification, illustrate embodiments of theinvention and together with the description serve to explain theprinciples of the invention.

[0031] In the drawings:

[0032]FIG. 1 is a sectional view showing a related art liquid crystaldisplay device;

[0033]FIG. 2 is a schematic view showing a double-faced display devicebased on the related art liquid crystal display device;

[0034]FIG. 3 is a sectional view showing a double-faced liquid crystaldisplay device according to one embodiment of the present invention;

[0035]FIG. 4 is a block diagram showing a double-faced liquid crystaldisplay device of a mobile telecommunication terminal according to thepresent invention;

[0036]FIG. 5 is a schematic view showing a display device of a mobiletelecommunication terminal when a folding cover is open, according to anembodiment of the present invention; and

[0037]FIG. 6 is a schematic view showing the display device of FIG. 5when the folding cover is closed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Reference will now be made in detail to preferred embodiments ofthe present invention, examples of which are illustrated in theaccompanying drawings.

[0039] As shown in FIG. 3, a liquid crystal display device 100 includesa lower substrate 100 b, an upper substrate 100 a, and a liquid crystallayer 100 c. A scan electrode pattern, a signal electrode pattern, and apixel electrode pattern are formed in the lower substrate 100 b, and anorigination layer is formed on the above patterns. A common electrodepattern and a color filter layer are formed in the upper substrate 100a. The liquid crystal layer 100 c is implanted into an aperture betweenthe upper substrate 100 a and the lower substrate 100 b.

[0040] The liquid crystal layer has a first switching state in which thephase of light is changed while passing through it and a secondswitching state in which the phase of light is not changed while passingthrough it.

[0041] The liquid crystal display device 100 is divided into a firstregion A and a second region B at a predetermined ratio by setting areference line R so that characters, numbers or figures are displayed indirection A and direction B.

[0042] When the liquid crystal display device is divided into the firstregion A and the second region B, the first and second regions A and Bcommonly include m signal lines, the first region includes 1^(st) to kthscan electrodes of the n scan electrodes, and the second region includes(k+1)th to nth scan electrodes of the n scan electrodes.

[0043] Alternatively, the first region A and the second region B maycommonly include n scan electrodes, the first region may include 1^(st)to kth signal lines of the m signal lines, and the second region mayinclude (k+1)th to mth signal lines of the m signal lines. The firstregion is greater than the second region.

[0044] To compensate a phase difference due to refraction of light whencharacters, numbers or figures are displayed, a first front polarizer101 and a second rear polarizer 102 are respectively disposed on andbelow the first region A of the liquid crystal display device 100. Toreflect light generated in the liquid crystal in direction A, a secondreflector 103 is disposed below the second rear polarizer 102.

[0045] Also, in the liquid crystal display device 100 divided throughthe reference line R, a first rear polarizer 102 a and a second frontpolarizer 101 a are respectively disposed on and below the second regionB to compensate the phase difference generated by refraction of lightwhen characters, numbers or figures are displayed. A second reflector103 a is disposed on the first rear polarizer 102 a.

[0046] In other words, the first front polarizer 101 is substantiallyaligned with the second rear polarizer 102 and the second reflector 103.The second front polarizer 101 a is substantially aligned with the firstrear polarizer 102 a and the first reflector 103 a.

[0047] The electrode patterns of the liquid crystal display device 100may have a dot matrix structure, a segment structure, or a mix of thedot matrix and segment structures.

[0048] In the case where the double faced liquid crystal display devicedivided around the reference line R is mounted into a folding cover of amobile telecommunication terminal, the first region A of the liquidcrystal display device is viewable on an inner surface of the foldingcover and acts as a main screen while the second region B is viewable onan outer surface of the folding cover and acts as a sub screen. Adetailed state of the liquid crystal display device will be describedwith reference to FIGS. 5 and 6.

[0049]FIG. 5 is a schematic view showing a display device of the mobiletelecommunication terminal when the folding cover is open, according tothe present invention, and FIG. 6 is a schematic view showing a displaydevice of the mobile telecommunication terminal when the folding coveris closed, according to the present invention.

[0050] As shown in FIG. 5, the mobile telecommunication terminalincludes a main body 230 and a folding cover 210. The main body 230 andthe folding cover 210 are connected with each other by a hinge 240. Aswitch 220 is provided in the main body 230 to detect the open andclosed states of the folding cover 210. The first region A of the liquidcrystal display device is displayed on the inner surface of the foldercover 210 as a main screen 200 a while the second region B thereof isdisplayed on the outer surface of the folding cover 210 as a sub screen200 b.

[0051] The system for driving a display device of the mobiletelecommunication terminal according to the present invention will bedescribed with reference to FIG. 4. As shown in FIG. 4, the displaydevice of the mobile telecommunication terminal includes a controller140, a RAM 150, ROM 160, an LCD controller 170, a frame memory 180, anda liquid crystal display device 190 divided into the two regions asdescribed above.

[0052] The controller 140 controls the overall operation of the liquidcrystal display device 190. Particularly, as shown in FIG. 5, thecontroller 140 activates the first region A viewable on the innersurface of the folding cover 210 in accordance with a signal from theswitch 220, which is switched by the open and closed state of thefolding cover 120. Alternatively, as shown in FIG. 6, the controller 140activates the second region B viewable on the outer surface of thefolder cover 210 to provide information on a calling party, including acalling party's name and the like, in case of a termination signal, andpossibly other information such as current time and/or battery status.

[0053] The RAM 150 acts as a volatile memory device and temporarilystores input signals or boot data so that the processing operation ofthe controller 140 can promptly be performed. The ROM 160 acts as anonvolatile memory device and stores the overall operational algorithmof the controller 140.

[0054] The LCD controller 170 controls the driving of the m signalelectrodes and the n scan electrodes in accordance with the controlsignal applied to display characters, numbers or figures, so that thefirst region and the second region on the inner and outer surfaces ofthe folder cover 210 are selectively displayed.

[0055] In other words, in case where the first region and the secondregion commonly include the m signal lines, the first region includes1^(st) to kth scan electrodes of the n scan electrodes, and the secondregion includes (k+1)th to nth scan electrodes of the n scan electrodes,the controller 140 controls the LCD controller 170 to display the firstregion of the liquid crystal display device if it is determined by thefolder switch 220 that the folding cover 210 is opened. Accordingly, theLCD controller 170 applies the driving signal to the signal line and thescan line within the limits of the 1^(st) to kth scan electrodes of then scan electrodes, so that the first region is only displayed. Bycontrast, if it is determined by the folder switch 220 that the foldingcover 210 is closed, the controller 140 controls the LCD controller 170to display only the second region. Accordingly, the LCD controller 170applies the driving signal to the (k+1)th to nth scan electrodes.

[0056] The frame memory 110 processes the applied signal for controllingdisplay for the unit of frame so that corresponding characters, numbersor figures can stably be displayed.

[0057] As aforementioned, the operation of the liquid crystal displaydevice of the present invention applied to the mobile telecommunicationterminal as shown in FIGS. 5 and 6 will be described.

[0058] In a state that the power is supplied to the mobiletelecommunication terminal, if a system-on signal is detected, thecontroller 140 analyzes the signal from the folder switch 220 switchedin accordance with open and closed state of the folding cover 210 whichis opened or closed around a shaft of the hinge 240.

[0059] If it is recognized by the signal of the folder switch 220 thatthe folding cover 210 is closed, the controller 140 determines that theoverall information is to be displayed through the second region B, andapplies the control signal to the LCD controller 170.

[0060] At this time, the LCD controller 170 displays information on acalling party's phone number, a received character message, currenttime, battery status and the like through the second region B inaccordance with the control signal.

[0061] Thereafter, in a state that the overall information of the mobiletelecommunication terminal is displayed through the sub screen 200 bviewable on the outer surface of the folding cover 210, if the opensignal of the folding cover 210 is detected by the controller 140through the folder switch 220, the controller 140 applies the controlsignal for displaying the first region A to the LCD controller 170. Thecontroller 140 activates the main screen 200 a on the inner surface ofthe folder cover 210 by appropriately selecting a contact point of thescan electrode and the signal electrode, and at the same timeinactivates the sub screen 200 b.

[0062] As aforementioned, the liquid crystal display device having adouble-faced display function has the following advantages. Since oneliquid crystal display device is divided into two regions, i.e., firstand second regions, and one driver dives the first region in a frontdirection and the second region in a rear direction, the double faceddisplay device is realized without two separate liquid crystal displaydevices, thereby effectively using a limited area. This achieves alight-weight and slim-sized mobile telecommunication terminal.

[0063] Furthermore, the double-faced liquid crystal display device isapplied to the folder of the mobile telecommunication terminal so thatinformation on a calling's party, a received message, current time, andthe like can be displayed even when the folding cover is closed.Accordingly, information to be displayed can be viewed even when thefolding cover is not open.

[0064] Still further, since the liquid crystal display device having adouble-faced display can be driven by one driver, power consumption canbe reduced. In addition, in case where the liquid crystal display deviceis applied to the mobile telecommunication terminal, it is possible toincrease the useable time of the mobile telecommunication terminal byone time charge.

[0065] It will be apparent to those skilled in the art that variousmodifications and variations can be made in the liquid crystal displaydevice and the mobile telecommunication terminal using the sameaccording to the present invention without departing from the spirit orscope of the invention. Thus, it is intended that the present inventioncovers the modifications and variations of the invention provided theycome within the scope of the appended claims and their equivalents.

What is claimed is:
 1. A liquid crystal display device comprising: afirst substrate having a common electrode; a second substrate having nscan electrodes and m signal electrodes; a liquid crystal layer disposedbetween the first and second substrates; a polarizer; and a reflector,wherein the liquid crystal display device is divided into a first regionand a second region, and the polarizer and the reflector are divided anddisposed so that the first region is displayed in a first direction andthe second region is displayed in a second direction, the firstdirection being opposite from the second direction.
 2. The liquidcrystal display device as claimed in claim 1, wherein the first regionand the second region commonly include the m signal electrodes, thefirst region includes first to kth scan electrodes of the n scanelectrodes, and the second region includes k+1th to nth scan electrodesof the n scan electrodes.
 3. The liquid crystal display device asclaimed in claim 1, wherein the first region and the second regioncommonly include the n scan electrodes, the first region includes firstto kth signal electrodes of the m signal electrodes, and the secondregion includes k+1 to mth signal electrodes of the m signal electrodes.4. The liquid crystal display device as claimed in claim 1, wherein thepolarizer comprises first and second polarizers respectively formed overthe first substrate and below the second substrate, and the reflectioncomprises a first reflector formed below the second polarizer of thefirst region, and a second reflector formed over the first polarizer ofthe second region.
 5. The liquid crystal display device as claimed inclaim 1, wherein at least a portion of the signal electrodes and thescan electrodes are formed in a dot matrix pattern.
 6. The liquidcrystal display device as claimed in claim 1, wherein at least a portionof the signal electrodes and the scan electrodes are formed in a segmentpattern.
 7. The liquid crystal display device as claimed in claim 1,wherein at least a portion of the signal electrodes and the scanelectrodes are formed such that a first portion of the signal and scanelectrodes are formed in a dot matrix pattern and a second portion ofthe signal and scan electrodes are formed in a segment pattern.
 8. Theliquid crystal display device of claim 1, wherein the liquid crystallayer has a first switching state in which a phase of light is changedwhile passing through it and a second switching state in which the phaseof light is not changed while passing through it.
 9. The liquid crystaldisplay device of claim 1, further comprising first and secondelectrodes for applying an electric field to the liquid crystal layer.10. A liquid crystal display device comprising: a first substrate; asecond substrate disposed below the first substrate; a liquid crystallayer disposed between the first substrate and the second substrate; afirst front polarizer disposed above and extending over a first portionof the first substrate; a first rear polarizer disposed above andextending over a second portion of the first substrate; a firstreflector disposed above the first rear polarizer and extending over thesecond portion of the first substrate; a second rear polarizer disposedbelow and extending under a first portion of the second substrate; asecond reflector disposed below the second rear polarizer and extendingunder the first portion of the second substrate; and a second frontpolarizer disposed below and extending under a second portion of thesecond substrate.
 11. The liquid crystal display device of claim 10,wherein the first front polarizer is substantially aligned with thesecond rear polarizer and the second reflector.
 12. The liquid crystaldisplay device of claim 10, wherein the second front polarizer issubstantially aligned with the first rear polarizer and the firstreflector.
 13. A liquid crystal display device having a first side andan opposite second side, and a first portion and an adjacent secondportion, the first portion being viewable from the first side andsubstantially not viewable from the second side, and the second portionbeing viewable from the second side and substantially not viewable fromthe first side.
 14. A mobile telecommunication terminal comprising: afolding cover movable between an open position and a closed position,the folding cover having a window in a predetermined area; a liquidcrystal display device having a first region and a second region, thefirst and second regions being viewable from opposite sides of theliquid crystal display device, the liquid crystal display device beingmounted on an inner side of the folding cover to externally display thesecond region through the window; and a driver for driving the liquidcrystal display device.
 15. The mobile telecommunication terminal asclaimed in claim 14, further comprising a folder switch for detectingopen and closed states of the folding cover, and a controller forcontrolling the driver to display information in the first region or thesecond region of the liquid crystal display device in accordance withthe folder switch.
 16. The mobile telecommunication terminal as claimedin claim 15, wherein the controller controls the first region to bedisplayed when the folder cover is open.
 17. The mobiletelecommunication terminal as claimed in claim 15, wherein thecontroller controls the second region to be displayed when the foldercover is closed.